Toremifene: where do we stand?

Abstract Toremifene is a chlorinated triphenylethylene that is indicated for postmenopausal breast cancer. For advanced disease, toremifene has been found to be as effective and at least as well tolerated as tamoxifen. The same appears to apply for adjuvant setting. After a total cumulative clinical exposure to toremifene of approximately 140 000 patient-years, only 9 cases of endometrial carcinoma have been reported. The annual hazard rate (per 1000 patient-years) of developing endometrial carcinoma in breast cancer patients on adjuvant toremifene is 1.14 (versus tamoxifen 2.0 and placebo 0.4). Although toremifene (being a partial agonist) may unmask pre-existing endometrial tumours, there is no clinical data implying that it would per se cause endometrial carcinoma.